It can be easy to fall into a funk. Your daughter didn't call last week. Your spouse left a sink full of dirty dishes. Your neighbor left the garbage cans out for three days. Again.

Focusing on the not-so-great things that happen regularly can add up to a lot of unhappiness – if you let it.

"What people spend their time and mental energy on becomes their reality, and unfortunately, so many people get in the habit of focusing on the negative," says Suzi Murphy, a wellness specialist who works for Blue Cross and Blue Shield.

But she says it can be just as easy to choose to be happy. She offers these paths to more happiness:

Each morning for 21 days, write down five things you're grateful for. By the end of three weeks, you will have retrained your brain to focus on gratitude.

At the end of each day, jot down a positive experience you had that day. Repeat for 30 days.

Simply your life. We are all so busy, we feel like we have to do two or more things at once. Slow down. Focus on one thing at a time. This will lessen your stress, which is sure to make you happier.

Focus on your strengths, not your weaknesses.

Exercise. Research shows that people who have just finished exercising can solve problems better, be more creative, and are more focused.

Try meditating. When you quiet your brain and focus on taking long, slow breaths in and out, it changes electrical brain impulses and calms your mind and body.

Sound easy? Then why is it so hard for people to choose to be happy? Because there are so many barriers that can trip us up along the way, Murphy says.

For example, writing in a journal requires having a notebook and a pen or pencil handy when the mood strikes. If you have to find a notebook or sharpen a pencil, it suddenly can seem like a chore. She recommends figuring out what barriers are keeping you from choosing to be happy, then creating ways around them.

If you want to write down five things to be grateful for each morning, keep a notebook and pen by your bed. You can reach the notebook and start writing before your feet even hit the floor. If you are reluctant to exercise, find an activity you like - walking, biking, swimming, dancing - and find someone to do it with you. You'll be more likely to go if you know a partner is waiting for you. You're also likely to have more fun, yet another good reason to choose to be happier.

A Division of Health Care Service Corporation, a Mutual Legal Reserve Company, an Independent Licensee of the Blue Cross and Blue Shield Association.